Vicken Y. Totten MD: Emergency Physician and Career-long Shift Worker
SLEEP in literature Sleep, that knits the ravell'd sleave of care, The death of each day's life, sore labour's bath, Balm of hurt minds, great nature's second course, Chief nourisher in life's feast. - - Shakespeare, Macbeth, Act II, Scene I
Goals and Objectives: Describe normal sleep structure Discuss Circadian Rhythm Disorders Describe types of shift work patterns Offer concrete shiftwork suggestions Provide a resource list
Biologic Rhythm Control Innate rhythms poly-genetically determined Master clock in suprachiasmatic nucleus of the rostro-ventral hypothalamus. Mediated by light/dark cycles via cryptopsin receptors in retina, skin and possibly pituitary Humans: Day = alert / Night = sleep.
Biologic rhythms All body systems change rhythmically 90 minute alertness cycle Monthly fertility cycle Sleep/wake generally 23-26 hour cycle
Rhythm disorders Normally, biologic cycles kept in synch by signal substances such as melatonin, cortisol and others Disruption in these systems have profound health implications. Disrupted by both internal and external signals Cycles re-synchronize at different rates
Circadian disruption De-synchronization of innate biologic / circadian cycles. Chronically in shiftwork and briefly from jetlag. Medicine is far behind industry in recognizing the implications of shift work
Causes of circadian rhythm disorders Genetics Medications Pregnancy Shift work time zone changes
Non-REM (NREM) sleep - Stages I-IV brain idle, body mobile REM - Body paralyzed, Brain active (more metabolically active than during waking)
Stage 1 - transition period. Normally 10 minutes. Eyes rove. Most people awakened during Stage 1 claim they are not asleep. “Micro-Sleeps” Driving while fatigued
Stage 2 - Deeper, fewer eye movements. Shallowest restorative sleep. About half of adult sleep in Stage 2. 20 min. before progressing to next stage.
Stages 3/4 - Slow wave sleep (SWS), (delta sleep) Most restorative & restful; vital for physical recuperation. Majority occurs early in the sleep period. Difficult to arouse from SWS. First stage to be “made up” after sleep deprivation. SWS deprivation causes fatigue, muscle aches.
REM sleep brain on, body off. Vital for psychological well-being; Isolated REM deprivation -> 1st irritability -> psychosis -> death EEG similar to wakefulness. Dreams, irregular pulse, respiration, increased BP, loss of muscle tone, and absent spinal reflexes.
REM sleep First episode occurs after 90-120 minutes of NREM sleep. Recurs in about 90 minute cycles, getting more frequent towards awakening REM periods become longer as night progresses. REM disorders include sleepwalking / talking / night terrors
“Core Sleep” Horne: first three SWS cycles with their REM periods "optional" sleep the rest of the night: more REM, less SWS Core sleep: about 5 hours for most persons Only core sleep made up.
“Sleepiness” 2 components: core versus optional missing core sleep (physiologic) -- disrupts physiologic systems missing optional sleep (psychological) -- mostly psychological / mood effects
Excess Sleepiness in Shift Workers
Circadian disruption Day /awake and night / sleep are the normal human condition. When switching to a day / sleep and night / awake, various physiologic cycles become desynchronized Hospitalization with loss of ‘Zeitgibers” Re-synchronization at different rates Generally, all systems can shift 1 hr per day.
Adverse Health effects of shiftwork Breast Cancer, Endometrial Cancer : increased in women who are not exposed to enough darkness; mechanism unclear; proposed mechanism is melatonin deficiency. Prostate Cancer: increased most in rotating shift workers when compared to fixed-night shift-workers, who have an extremely minimal risk. Pregnancy Issues: night work and high work load increase the risk of spontaneous abortion
Inter-relationships are complex Obesity, pregnancy, high fat diets and circadian rhythm Npas2 is a key organizer of the circadian system; if maternal diet is high fat, the fetal liver fetal histone code is mal-transcribed, and leads to appetite and circadian disorders in the offspring. www.bcm.edu/obgyn/index.cfm?pmid=11856
Common Circadian Rhythm Disorders Jet Lag or Rapid Time Zone Change Syndrome: Delayed Sleep Phase Syndrome (DSPS) Advanced Sleep Phase Syndrome (ASPD) Shift Work Sleep Disorder (SWSD)
Jet Lag / Shift work Personal cycles out of synchrony with local conditions. Sleepy when alertness is required; alert when sleep required Caused by travel across time zones, shift work and sometimes by adolesnce Can cause chronodysruption, since different systems re-synchronize at different rates.
Zeitgibers (from Gr. “Time Tellers”) the physical and social clues which tell us what time it is. Most powerful is light. Others include taste and smell of usual breakfast food, going to work, sound of daytime activities
Night Owls vs. Morning Larks Night people = easier adjustment to shift work Tend to be phase delayed Day people = harder with shift change; more stable once adjusted Tend to be more synchronized and more resistant to re-setting Residency survey: EP s have more night types than normal populations
Delayed Sleep Phase Syndrome (DSPS) A disorder of sleep timing. People with DSPS tend to fall asleep very late Difficulty waking up in time for work, school, or social engagements Common, perhaps normal in adolescence “Owls”
Advanced sleep-phase syndrome (ASPS) ASPS persistent early evening sleep onset time (between 6:00 pm and 9:00 pm) and spontaneous early morning wake-up time (between 3:00 am and 5:00 am). Variably associated with inadquate sleep. Associated with extreme age and depression. “Larks”
Non 24-Hour Sleep Wake Disorder (N24HS/W disorder): Innate 23-25 hr cycles constantly reset by zeitgibers Normal sleep pattern but inate cylce is neither firm nor maintained. Struggles with “Free cycling” Inconsistent insomnia that occurs at different times each night.
Definitions for Emergency Medicine On - call On duty Sleep deprivation Chronodisruption
On Call versus On Duty “On call”: night work between working days = pure sleep deprivation Possibility of sleep while on call Usually does not cause circadian rhythm disruptions -- body cycles remain in phase “On duty” implies expected time of usual type of work Isolated night shifts “on duty” (less than once per week) physiologically function as ‘on call’
Sleep deprivation loss of "optional sleep" (sleeping less than one's habit) causes drowsiness, no other serious effects "core sleep" deprivation (less than 5 hours of slow wave sleep) Sleep deprivation causes both physiologic and psychological ill effects
Shift work prevalence Not a new phenomenon, but now vastly more frequent. 25% of American workers are shift workers at some point in their lives. Invention of the light bulb: 1883
Shift work definition Work a defined period of time, then off for a period Working time can be at any time of the 24-hr day Fixed shifts -- working the same time every day Rotating shifts -- working time of day changes from time to time
Shift length length of shift: most common is 8 hours others are 10, 12 and 6 hours more mistakes made in the last 4 hours of a 12 hour shift than in the first 8 hours Shift changes become more difficult after age 40
Serious adverse health consequences of shift work 20% decrease in life span 62% sleep disturbance higher rate of accidents on the job high risks of fatal commuting accidents 800% risk of ulcers 1500% incidence of depression and mood swings
Shift work is also linked to: drug and alcohol abuse altered immune response infertility in women high divorce rate.
Cardiovascular effects of shift work is ... increased cardiovascular mortality (risk worse than smoking a pack of cigarettes per day) risk for dysrhythmias (PVC, MAT, SVT) risk of sinus arrest (up to 12 sec in one study)
Tolerance to shift work Better in younger persons (under 40, or pre-menopausal) Better in childless persons Better in natural owls than natural larks 20% of people have no trouble changing shifts, 60% have moderate hardship, and 20% have extreme difficulty.
Shift work patterns most work has been done on 8 hour shifts 12 hour shifts no longer permitted in most industries rotating shifts isolated shifts random shifts
Shift schedules Optimum: days only; in synchronous with your own best working time Next best: same shift every day, even if not most suited to your optimal time; or isolated nights Worst: randomly rotating shifts
Rotation patterns: Swing shifts Phase advance: one week days, one week evenings, one week nights Phase retreat: (Southern Swing): one week days, one week nights, one week evenings Of the two, phase advance is more physiologic and more easily tolerated
Randomly changing almost universally condemned forbidden by most unions highest physiologic risk and stress practiced mostly by physicians
Isolated nights equivalent to a bad night on call
Important! One can adjust by 1-2 hrs. / 24, or one week to move forward by one (8 hr) shift Therefore, maintain the same schedule when not working most permanent night workers switch to day-life when not at work and reap the same ill effects as random-shift changers Optimal: one month or more between changes
What about physicians? MD = Maximum Denial Socialized to ignore their own needs Trained to be ‘tough’ poor role models
Cardiovascular effects in physicians: palpitations and dysrhythmias Brodsky M, Wu D, Denes P, Kanakis C, Rosen KM: Arrhythmias documented by 24 hour continuous electrocardiographic monitoring in 50 male medical students without apparent heart disease. Am J Cardiology 1977;39:390-395
Cardiovascular effects sinus arrest with syncope in residents Guilleminault C, Pool P, Motta J, Gillis AM: Sinus arrest during REM sleep in young adults. NEJM: 1984;311:1006-10
More studies Physicians aren’t immune to poor health effects of shift work Åkerstedt T, Knutsson A, Alfredsson L, Theorell T: Shift work and cardiovascular disease. J Work Environ Health: 1984; 10:409-414 Åkerstedt T. Psychological and psychophysiological effects of shift work. Scand J Work Environ Health. 1990;16(suppl 1):67-73
Performance of physicians Poor performance with micro-sleeps (non-restorative) during rote tasks Documented micro and mini-sleeps during drive home even in those who did not think they had slept Åkerstedt et al: Physicians during and following night call duty--41 hour ambulatory recording of sleep. Electroencephalography & Clinical Neurophysiology: 1990; (76) 193-196
Physician learning Decreased performance, learning of deleterious habits and physiologic harm. Asken MJ, Raham DC: Resident Performance and Sleep Deprivation: A Review. J. Med Educ 1983;58:382-388
Overall performance Found that shift work affected rote tasks and the highest intellectual tasks equally as much; moderately challenging but well known tasks suffered least. Implication for physicians: we make more mistakes on the more serious cases Tilley et al The sleep and performance of shift workers. Human Factors, 1982; 24: 624-41
Exercise tolerance Sleep deprivation had little effect on acute exercise tolerance in normal persons Chen H: Effects of 30-h sleep loss on cardiorespiratory functions at rest and in exercise. Med Sci Sports and Exerc: 1991; 23(2):193-198
Shift length Used temperature as a marker for slowing of physiologic activities Concluded that 12 hour shifts lead to increased mistakes poorer per-hour productivity Daniel J, Potasova A; Oral temperature and performance in 8 h and 12 h shifts . Ergonomics 32(7):689-96 , 1989 Jul.
Strategies to improve health for shift workers sleep hygiene napping at work food & exercise social life
If you must be a shift worker: Learn how to sleep well Learn how to change your circadian rhythms smoothly Use circadian principles to make your work and home life better Educate your schedule-maker Educate and enlist your family
Living the Strategic Life Avoid vigorous exercise at least 4 hours prior to bedtime (Regular exercise is recommended.) Avoid cigarettes, alcohol, and caffeine 4-6 hours prior to bedtime Avoiding large meals and excessive fluids just before bedtime
Light therapy: Timing of light Minimum of 30-60 minutes not long after wakening to promote adaptation and wakefullness Re-synchronising ASPS light in the early evening and nighttime hours delays the cycle DSPS light therapy in the early morning hours stimulates morning alertness and an earlier bedtime.
Environmental control Light – adequate at work (6,000-7,000 Lux) Dark – during sleep time (less than full moon) (consider eye shades) Noise – shut out during sleep. Isolate sleep room, use earplugs Room temperature – warm sleepers vs cool sleepers Exercise, Diet
Sleep Hygiene Temperature: between 22 - 24 C Bedroom: Condition yourself that Bed = Sleep time Ritual: helps to create a ‘stimulus-response’ conditioning Keep sleep time sacred, and minimize care-giving responsibilities during that time.
Diet troubled by early awakening? => try bedtime snack. Milk products seem to improve sleep. Alcohol: a single drink can help tense people relax, but alcohol actually alters sleep structure by postponing REM Great care to eat appropriately during the working / waking time
Exercise Athletes: get more delta (SWS, restorative) sleep. Time of day important: pm exercise has more effect. Exercise should be completed more than one hour before sleep time
Light – most important for humans intensity is important: 7,000 Lux about the same as a heavily overcast day most indoor lighting is inadequate new ‘energy saving’ fixtures are even more inadequate implication to hospital administration: high intensity lights over physicians / nurses working areas improves productivity and minimizes mistakes.
Timing of light pulses is important 2-3 hours of high intensity light within one hour of awakening implication for shift workers: either go outside while the sun is still up before going to work the night shift, or buy and use a high intensity light at home Fluorescents in windows.
Drugs and Pharmacology Drugs to sleep or to wake or re-synchronize MDs: temptation and access to non-legal drug use health care shift workers are at high risk for drug addiction
Melatonin Melatonin is a re-synchronizer used in the treatment of circadian rhythm sleep disorder especially in blind persons OTC “diet supplement” dosing guidelines not established. My use: 6-6-3-3
Melatonin 3-6 mg, taken one hour prior to desired (new) sleep time Diminished (genetically?) in aging. Full effects of chronic exposure not yet known. Not FDA regulated, but seems to be extremely safe for brief use as in phase adjustment.
Melatonin stimulant Ramelteon (Rozerem) Rx only. stimulates melatonin release Ramelteon promotes the onset of sleep and helps normalize circadian rhythm disorders. Ramelteon is approved by the Food and Drug Administration (FDA) for insomnia characterized by difficulty falling asleep.
Hypnotics: Benzodiazipines Benzodiazepines: short acting for sleep onset or napping. Triazolam (Halcion) Medium or long-acting: for sleep maintenance. estazolam [ProSom] quazepam [Doral] Possibility of rebound insomnia
Benzodiazepines side effects can disrupt sleep architecture may have residual sedative effects lasting into the next working period many are fat soluble and will leach out over many days illegal in some working environments
Non-benzodiazepine hypnotics Less effect on sleep architecture than benzos, less rebound insomnia Zolpidem (Ambien) moderate to long acting Eszopicline (Lunesta) moderate duragion Zaleplon (Sonata) short acting
OTC hypnotics Benadryl – 25-50mg. Tachyphylaxis Alcohol – disrupts sleep architecture Herbs: hops, valerian, passion flower
Diphenhydramine / sedative antihistamines sedative antihistamines help induce sleep, and in some, help maintain sleep effect on sleep architecture is minimal tachyphylaxis: effects wane within days may produce prolonged sedation, interfering with performance and maintenance of new schedule when not at work
Alcohol disrupts sleep architecture delays REM sleep variable effect on sleep latency recommendation for shift workers: finish your alcohol more than one hour before scheduled sleep time
Cheat Sleep: stimulants OTC: primarily caffeine Illegal: Cocaine, “Speed” and various “uppers” Legal: - amphetamines and amphetamine –like drugs
- Ampakines and their sucessors
Amphetamines methylphenidate (Ritalin, Metadate, Concerta) dextroamphetamine Plus amphetamine (Adderall) Dextroamphetamine (Dexedrine) lisdexamfetamine dimesylate – metabolized to methamphetamine (Vyvanse)
Ampakines and their successors Modafinil (Provigil, Alertec, Modavigil, Modalert, Modiodal, Modafinilo, Carim, Vigia) analeptic drug manufactured by Cephalon, and is approved by the FDA for shift workers Armodafinil (Nuvigil) is the active (−)-(R)-enantiomer of the racemic drug modafinil Side effects include potentially cognitive enhancement, and loss of effect of BCPs
Caffeine harmless in small doses taking caffeine to get through the night shift may interfere with day sleep careful with timing of caffeine intake
bright light early in waking time significant exercise later in waking period optimize sleeping conditions: aluminum-foil on the windows, ear plugs, eye shades, fan stay on the same schedule without varying by more than an hour as long as you can Consider Melatonin.
Summary American society is more 24 / 7 EM always 24 / 7 Use circadian principles to improve your well being and prolong your professional life and your personal life
Resources American Academy of Sleep Medicine One Westbrook Corporate Center, Suite 920 Westchester, IL 60154 (708) 492-0930 National Sleep Foundation 1522 K Street, NW, Suite 500 Washington, DC 20005
Enhancing adaption Rotating shiftwork schedules: can we enhance physician adaptation to night shifts? Smith-Coggins R , Rosekind MR , Buccino KR , Dinges DF , Moser RP Acad Emerg Med 1997 Oct;4(10):951-61
Best single reference "Why we Sleep" by James Horne. Published by Oxford University Press Walton St Oxford OX2 6DP 1988 a classic overall reference
Web Links Northwestern University, Center for Sleep & Circadian Biology, About Circadian Rhythms National Sleep Foundation, Strategies for Shift Workers National Sleep Foundation, Sleep and the Traveler National Institute of Mental Health, How Biological Clocks Work Sleepnet.com
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